TPA3116D2 Amp

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#2,561
Lo_Tse,
Based on the fact that the TI engineers said it could be managed by proper PCB layout seems to suggest that the beat frequency modulation is caused by parasitic stray EM radiation pickup interference from one amplifier to the other because the inductors and leads are in close proximity on one PCB. The beat frequency is a signal that is generated by the mixing (or heterodyning) of two similar frequencies to generate the beat frequency which is equal to exactly the difference between the two. So if one amp has a modulation of 401kHz and the second is 400kHz, the beat frequency is 1kHz and at a very noticeable tone to the human ear. But if they are 400,020 Hz vs 400,000 Hz then the beat frequency is 20 Hz which is not that noticeable and kind of beyond the bandwidth of most speakers. My sub and the Ybdz amp is capable of producing some sound down there in the 70 dB level but I did not hear it nor did I see a significant peak in harmonic distortion.
 
#2,562
xrk971 said:
Lo_Tse,
Based on the fact that the TI engineers said it could be managed by proper PCB layout seems to suggest that the beat frequency modulation is caused by parasitic stray EM radiation pickup interference from one amplifier to the other because the inductors and leads are in close proximity on one PCB. The beat frequency is a signal that is generated by the mixing (or heterodyning) of two similar frequencies to generate the beat frequency which is equal to exactly the difference between the two. So if one amp has a modulation of 401kHz and the second is 400kHz, the beat frequency is 1kHz and at a very noticeable tone to the human ear. But if they are 400,020 Hz vs 400,000 Hz then the beat frequency is 20 Hz which is not that noticeable and kind of beyond the bandwidth of most speakers. My sub and the Ybdz amp is capable of producing some sound down there in the 70 dB level but I did not hear it nor did I see a significant peak in harmonic distortion.
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I do not recall seeing any posts related to this issue so far. So, may be that this "heterodyning" is not really a concern in our case.

Regards,
 
#2,563
Virpz said:
Great build you have done there.
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Thanks Virpz!

Btw, is the an connection guide to wire the Audiobah boards in mono?

xrk971 said:
What is a miniDC? I just take some cheap old RCA to RCA cables and cut them in half and solder the flying leads to the amp input then plug the other end to the miniDSP. I found a source of cheap RCA PCB board jacks for like $0.50 a pair. If we want to take advantage of low noise capability of amp we should use preamps with balanced outputs.
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MiniDC is a noise filter from Minidsp, also it manages remote turn on/off of amplifiers. Check their website.

Since I am powering the dsp via USB (via the brick feeding the PC), I get a higher noise floor.
 
#2,564
Hi all,

I bought one of the enclosed red amps:

Finished TPA3116 2.1 50W+ 50W+100W Class D AMP Amplifier Board
Finished TPA3116 2 1 50W 50W 100W Class D AMP Amplifier Board | eBay

I conected it to this DAC, which in turn, is connected to a Raspberri Pi (Sqeezebox is used for streaming music):

1PC 5V USB Powered PCM2704 MINI USB Sound Card DAC decoder board
1pc 5V USB Powered PCM2704 Mini USB Sound Card DAC Decoder Board | eBay

The amp is connected to a pair of Yamaha outdooor speakers. I found that the maximum volume of the system is not quite enough, so I'm wondering whether it could be an issue with the impedance, gain, etc. Any ideas on what I can try to boost the volume?

For now, I've connected a Sure headphone amplifier between the DAC and the amp, which gives the required boost in volume.

2 X 150 mW Class-AB Headphone Amplifier Board – LM4881 150mW Stereo HP Amp
2 X 150 MW Class AB Headphone Amplifier Board ? LM4881 150mW Stereo HP AMP | eBay

Thanks!
Joe
 
#2,572
When seller cancels order you already paid for on Aliexpress, claiming you ordered inferior product he can't sell, Aliexpress gives you back $$ you paid minus $15....Seller keeps offering the same product, like others do, sometimes may be sending them to buyers, who knows, complaining about this doesn't get answered by Aliexpress and a negative feedback is counted as 100% positive. So really much better....AliExpress is making money by dishonest sellers and does not remove them or their offers.
 
#2,575
PMental said:
That's not true at all: http://tinyurl.com/o3mpj2t (<-link to Ebay, had to use tinyurl to make it work)

As long as you open a case within 30 days you will get your money back unless it can be resolved with the seller.
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For me, shipping times via Ebay are much better and the one item purchased on Ebay that was received DOA (out of over 50 purchased in the past six months) was replaced promptly by the seller, no questions asked.
 
#2,577
Prezden,
Do you get your Sure tpa3110 boards direct from Sure? Those are available on PE for $10 so it's a no brainer when I order other stuff to throw it in. My next amp will be the Danzz YJ Blue and I will get that direct as I hear that shipping is quick. Aliexpress gave me full refund - which was a surprise. Amazon also carries whatever PE sells so sometimes I get it there.
 
#2,579
As has been pointed out already, at least with eBay you know who your reliable sellers are. I only work with about 5, and 90% of that is with just 1. So far for me, AliExpress might as well put the package on a donkey and have it swim across the ocean. It would get here sooner. By the time stuff started to arrive 2 months later, I had forgotten what I ordered. How sick is that?

Remember the seller that cancelled one of the little amp boards due to a defect, or safety issue? They never did say how they would resolve it. I told them I wanted a refund, but never got a notice that it was ever refunded. I wasn't too worried for $13.99 or whatever amount it was. I think those boards showed up last week with the heat-sink bouncing around in the soft bag they were shipped in. :worried:

Rick
 
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